These drama's have A LOT of similarities. Both of the leading males are rich and they both have similar friendly & supportive secretaries. Both of the male leads have a close friend/brother who becomes somewhat of a love rival, and like the same girl. & there's more that I just can't think of now.
Both tells a story about a girl with some money issues. In both dramas the girl has 2 guys who likes her and what's even better; in both dramas the guys are cousins. Both of these dramas have super hilarious comedy and similar female leads. Oh well but it's a given since the female lead is played by the always so amazing Lee Da Hae ^^
Both are very fun to watch, have that loud and quirky heroine and in contrast the cold, quite hero (well the guy in my girl isnt that mean, but you know...!)And of coarse there is the pitiful second guy who is absolutely obsessed with the girl, but she cant help but be in love with the mean guy. And both feature the ex girlfriends that you wanna murder.
The big similarity between these dramas is the deception of the main female playing a rich (heiress) girl when she is actually rather poor and working several jobs. Money is the main protagonist into making them take this step (although Lee Da Hae plays more of a con artist, while Yang Jin Sung plays the hardworking innocent girl), which in both cases concludes into the girls falling in love with someone they supposedly have no right to. There is also a fall in the shower/barthroom scene in both dramas ;) Also, the forbidden love between siblings (as much as the leads can be considered siblings, when everything is only a con) takes on only a subplot in Bride of the Century, while My Girl lives out every angsty moment of it. Though, the big dissimilarity between these dramas is the supernatural/horror plot to the Bride of the Century - nevertheless, both dramas never fail to deliver the comical moments, as the girls bring their own breezy thinking into the lives of the stiffly rich.
Plot-wise these two have pretty much nothing in common. If you enjoy the acting of the female lead on the other you will enjoy the acting in the other one too. I personally found the female leads pretty similar with their over-acting characters and tacky clothing. They're similar to the point I would think they're siblings.
Both have the same writers (Hong Sisters) and even though the stories seem to be quite different you will realize that they have some points in common. For example: Like Joong Won, Seol Gong Chan is a CEO (but a hotel instead of a shopping mall)& acts cold towards the female lead but is willing to help her later on,in both the female lead keeps annoying the male lead in the beginning. Female lead feels lonely in both. I can't think of other similarities right now (And I don't want to spoil it for you).You will see while watching :)